title: Environmental risk factors for pulmonary Mycobacterium avium-intracellulare complex disease.
abstract: BACKGROUND
  Mycobacterium avium-intracellulare complex (MAC) is a ubiquitous pathogen found in soil and water. Environmental exposure is the primary route for MAC infection. However, specific environmental risk factors have been poorly determined in immunocompetent patients with pulmonary MAC disease.
  
  
  METHODS
  A case-control study was performed with 106 patients with pulmonary MAC disease (men [women], 23 [83]; age, 64.3 ± 9.2 years) and 53 age-matched control patients with bronchiectasis but not pulmonary MAC infection (men [women], 7[46]; age, 63.0 ± 11.0 years). All participants completed a standardized questionnaire that included questions about medical history, smoking history, alcohol usage, age at menopause, and environment exposures. Environment exposures included soil exposure from farming or gardening; water exposure from bathing, showering, hot tub use, dishwashing, swimming, and drinking water; and pet exposure.
  
  
  RESULTS
  No differences were identified in the patient characteristics and underlying diseases. More case patients experienced high soil exposure (≥ 2 per week) than control patients (23.6% vs 9.4%, P = .032); this remained significant after multivariate analysis (OR, 5.9; 95% CI, 1.4-24.7; P = .015). There were no significant differences in other environmental exposures. Case patients with high soil exposure were significantly older than those with low soil exposure (67.3 ± 7.3 years vs 64.3 ± 9.5 years, P = .037). Other characteristics, underlying diseases, and mycobacterial species did not differ between the two groups.
  
  
  CONCLUSIONS
  Patients with pulmonary MAC disease had significantly more soil exposure than noninfected control patients, which suggests that environmental soil exposure is a likely risk factor for the development of pulmonary MAC disease.
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto.
authors.forename: Koichi
authors.initials: K
authors.lastname: Maekawa
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto. Electronic address: yutaka@kuhp.kyoto-u.ac.jp.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Ito
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto.
authors.forename: Toyohiro
authors.initials: T
authors.lastname: Hirai
authors.affiliation: Department of Nuclear Medicine and Diagnostic Imaging, Graduate School of Medicine, Kyoto University, Kyoto.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kubo
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto.
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Imai
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto.
authors.forename: Shuji
authors.initials: S
authors.lastname: Tatsumi
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto.
authors.forename: Kohei
authors.initials: K
authors.lastname: Fujita
authors.affiliation: Department of Clinical Laboratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto.
authors.forename: Shunji
authors.initials: S
authors.lastname: Takakura
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto.
authors.forename: Akio
authors.initials: A
authors.lastname: Niimi
authors.affiliation: Department of Infectious Diseases, Kanazawa Medical University, Kanazawa, Japan.
authors.forename: Yoshitsugu
authors.initials: Y
authors.lastname: Iinuma
authors.affiliation: Department of Clinical Laboratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ichiyama
authors.affiliation: Department of Nuclear Medicine and Diagnostic Imaging, Graduate School of Medicine, Kyoto University, Kyoto.
authors.forename: Kaori
authors.initials: K
authors.lastname: Togashi
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto.
authors.forename: Michiaki
authors.initials: M
authors.lastname: Mishima
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D008171:Lung Diseases / Q000453:epidemiology / Q000382:microbiology*; D008297:Male; D008875:Middle Aged; D015270:Mycobacterium avium-intracellulare Infection / Q000453:epidemiology*; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000382:microbiology; D012307:Risk Factors; D012988:Soil Microbiology